Effects of angiotensin and noradrenaline on atrial natriuretic peptide levels in man.

1. A significant positive correlation was found between changes in circulating noradrenaline (NA) levels and changes in atrial natriuretic peptide (ANP) levels during NA infusion and clonidine administration. 2. A significant positive correlation was also found between changes in arterial blood pressure and changes in ANP level during infusion of angiotensin II and of NA. 3. Two patients with very high circulating NA levels due to phaeochromocytoma, but receiving alpha- and beta-blockade, did not have clearly elevated ANP. A third not receiving medications and aged 73 years had elevated levels. 4. Atrial natriuretic peptide response to NA and angiotensin II may be mediated by changes in blood pressure levels or increased noradrenergic and angiotensinergic receptor activity in the atria or both. Atrial natriuretic peptide may have a role in blood pressure regulation in both normotensive and hypertensive man.